Art of refining



Patented Feb. 20, 1940 ran STATES ART OF REFINING Edwin J. Barth,Chicago, HL, assignor to Sinclair Refining Company, New York, N. Y.', acorporation of Maine No Drawing.

Application May 5, 1936,

Serial No. 77,926

3 Claims.

This invention relates to improvements in petroleum hydrocarbon oils.More particularly, it relates to inhibition of oxidation in petroleumoils, lubricating oils in particular, having a Saybolt Universalviscosity upwards of 50 seconds at 100 F. by the addition thereto of anorganic oindation inhibitor. The invention includes a new organicoxidation inhibitor and an improved compounded petroleum oil containingthe new oxidation inhibitor of the invention.

Petroleum oils have a tendency to form sludge and gummy and resinoussubstances. The formation of these substances is generallyobjectionable, particularly so where it is desired to main 5 tain theoil in a continuously uniform condition. One generally acceptedexplanation assumes that the formation of these substances results fromoxidation. Whatever may be the true explanation, it is known that whenlubricating oils are gen used in internal combustion engines, forexample, these undesirable substances form and. as formed, are commonlyreferred to as sludge.

Sludge may appear in a variety of forms ranging from deposits quite softand gelatinous in as nature to those of the texture of coke. The resultsarising from the presence of sludge deposits are varied, ra fromaccumulations in oil pans and other relatively stat locations whichappear objectionable but which actually do no harm, to deposits in suchvulnerable spots as ring grooves, 011 screens and filters, where actualinterference with engine operation occurs. Sludge, in addition to beingobjectionable in the respects noted, causes an increase in viscosityaccompanied by an increase in the variability of viscosity withchangingtemperature. Where the maintenance of continuously uniformproperties is desirable, such changes are, of course, objectionable.

In accordance with the present invention. sludge formation and suchchanges with respect to viscosity are inhibited, thereby promotinguniformity of properties and in the useful life of the oil, the periodover which those prop- 45 erties remain within limits appropriate to theparticular use.

It is an object o! the present invention to provide an oxidationinhibitor which when incorporated in petroleum oils in proper proportionwill m minimize or inhibit oxidation of the oil. A further object of theinvention is to provide a compounded petroleum oil containing the newinhibitor of the invention which has greatly reduced tendencies to formsludge and similar oxidation products. A still further object is toprovide an oxidation inhibitor which when incorporated in a petroleumoil, as defined herein, will inhibit oxidation and reduce the tendencyof the oil to undergo changes with respect to viscosity. I I havediscovered that phenyl ether CcHsOCeHsZ exhibits excellent oxidationinhibiting properties. When added to'petroleum oil having a SayboltUniversal viscosity upwards of 50 seconds at 100 F., in amountapproximating 0.1% by weight, for example, oxidation, with its resultantsludge formation is markedly inhibited and changes with respect toviscosity are retarded.

It might be noted that extensive investigations have shown thatsubstances known to be oxidation inhibitors in arts other than thepetroleum art have little or no value as applied to petroleum oils. In anumber of instances tests have shown that some of these known oxidationinhibitors were detrimental when incorporated in petroleum oil andactually caused an increase in the rate of sludge formation.

As the value of an oil which is to be used over and over again, orsubjected to continuous use, for example, depends largely upon itsstability, tests have been devised to'determine the stability of an oilin particular respects. Thus tests have been developed which enable oneto determine to what extent an oil will sludge when in use, and

these tests furnish a means for evaluating the oil in this respect andto determine the efliciency of oxidation or sludge inhibitors. One ofthese tests is known as the Indiana Oxidation Test. test is described inan article entitled Causes and effects of sludge formation in motor oil"appearing on pages 167, 168 and 181 of the Journal of the Society ofAutomotive Engineers for May, 1934, where the problem of sludgeformation is treated at considerable length. This Indiana OxidationTest" to which reference is made hereinafter, oflers a means ofdetermining the socalled sludging time or an oil. 1

In this test 300 cc. of the oil to be tested are placed in a glass tubetwenty inches long by one This and three-quarter inch internal diameter,se-

cured in an oil bath maintained at a temperature sufiicient to keep thetest oil at 341 F. The level of the oil in the tube should be well belowthe bath level. Air is passed through the oil, being introduced througha glass tube of three-six teenth inch internal diameter at a point aboutone-quarter inch from the bottom of the glass tube at a rate of tenliters per hour. Periodically, depending on the oxidationcharacteristics of the oil, cc. of oil are removed, 10 grams of whichare immediately weighed into a tared Erlenmeyer flask. This portion isdiluted with 100 cc. A. S. T. M. precipitation naphtha and allowed tostand three hours before filtering throughaGooch crucible. The cruciblecontaining the insolubles is washed with approximately 100 cc. ofnaphtha after which it is dried one-half hour at 300 F. and weighed. Theamount of insoluble matter is expressed in milligrams per ten grams ofoil. A sufficient number of samples should be taken for test todetermine accurately the sludging time, that is, the time required toform ten milligrams of naphtha insoluble matter per ten grams of oil.When employing the above test it is common to also determine the 100milligram point, i. e., the time to form 100 milligrams of insolubles,but it will be understood that the sludging time is the time required toform 10 milligrams of naphtha insoluble material per 10 grams of oil.

The determination of viscosity increase, which becomes the moreimportant criterion when the sludging time is much over 50 hours, ismade by taking a 100 cc. sample every 50 hours. This sample is promptlyrun for viscosity and put back in the oxidation tubes. Oxidation testsare ordinarily continued either to the 100 milligram point or forv 150to 200 hours for so-called sludgeless oils. 1

The following example will illustrate the invention:

0.10 percent by weight of phenyl ether is added to an oil having anIndiana sludging Time of 21 hours and a viscosity rise of 9.50 seconds(Saybolt Universal) at 210 F. after 50 hours. Upon test the oil, withadded phenyl ether, was found to have an Indiana Sludging Time of 58hours. No viscosity rise at 210 F. after 50 hours occurred.

The oil employed in the foregoing example was of Mid-Continent base andhad the following characteristics Gravity A. P. I 24. 8 Viscosity at 100F Saybolt UniversaL- 513 Viscosity at 210 F do 60- 6 Viscosity index79.2 Flash point F 435 Fire point F 500 Pour point ..F 0 Acid number.025 Iodine number 20. 2

Aniline point c 97. 5

The proportion of phenyl ether to be incorporated in any given oil toobtain optimum results will vary depending upon the oil itself. Theproportion of phenyl ether approximating that added to the oil in theforegoing example, is generally advantageous.

While the invention is generally applicable to petroleum oils having aSaybolt Universal viscosity upwards of 50 seconds at 100 F., it isprimarily concerned with petroleum oils, lubricating oils, for example,and heavy lubricating oils in particular, which are subjected tocontinuous use, as opposed to petroleum oils which are immediatelyconsumed in use, and it is in this connection that the invention has itsgreatest utility. Where oil is to be consumed, burned for heatingpurposes in an oil heater, for example, the invention is not of equalimportance as when the oil is being used over and over again, sinceutilization of an oil for burning involving destruction of the oil isinconsistent with its preservation for reuse. Again, for such purpose itis of less consequence that the oil have high resistance to sludgeformation and changes with respect to viscosity since the oil is beingsubjected to a use where these properties are of secondary importance.In either case, however, the addition of the oxidation inhibitor of theinvention, in proper proportion, will inhibit sludge formation andretard changes with respect to viscosity, but its utility in one case isgreater than in the other.

The terms oxidation inhibitor and oxidation as used herein and in theclaims are intended to be used in their broad rather than their narrowsense. Oxidation is intended to refer to the manner of formation of theundesirable substances in the oil, regardless of the precise manner oftheir formation. The inhibitor employed to retard or limit the formationof these undesirable substances has been termed an oxidation inhibitorin the same sense.

I claim:

1. A petroleum lubricating oil having a Saybolt Universal viscosityupwards of 50 seconds at 100 F. containing about 0.1% by weight ofphenyl ether.

2. A petroleum lubricating oil having a Saybolt Universal viscosityupwards of 50'seconds at 100 F. containing phenyl ether in amountsuflicient substantially to inhibit'oxidation of the oil.

3. A petroleum oil having a Saybolt Universal viscosity upwards of 50seconds at 100 F. containing phenyl ether in amount suflicientsubstantially to inhibit oxidation of the oil.

EDWIN J. EARTH.

